This chapter discusses the rock cycle and each of the three major types of rocks that form on Earth. Separate sections cover igneous, sedimentary, and metamorphic rocks individually.
TYPE OF ROCKS
...Metamorphic rocks form when an existing rock is changed by heat or pressure. The minerals in the rock change but do not melt (Figure below). The rock experiences these changes within the Earth.
This mica schist is a metamorphic rock. It was changed from a sedimentary rock like shale.